3–32 Copyright © 1996 General Motors Corp.
AT 500, 1500 SERIES AUTOMATIC TRANSMISSIONS
A. Slippage
†
/** (cont’d)
Slippage in first range and in
reverse; proper function in other
forward ranges
First clutch slipping. Overhaul clutch and replace piston
seals. Refer to Paragraphs 5–3q and
7–4a.
Piston sealrings cut. Replace sealrings. Refer to Para-
graphs 5–3p and 7–4a.
Clutch-apply feed tube loose or
leaking.
Reset or replace feed tube. Refer to
Paragraphs 5–3h and 7–10a.
B. Excessive Flare — Engine Speed Rise on Full-Throttle Upshifts
Excessive engine flare Sticking trimmer valve. Replace or rebuild main control
valve body assembly. Inspect trim-
mer valves and confirm correct
springs. Refer to Paragraph 6–6.
Incorrect or weak trimmer valve
springs.
Replace or rebuild main control
valve body assembly. Refer to Para-
graph 6–6. Check trimmer valve
springs. Refer to Paragraph 8–2.
Piston seals leaking or clutch plates
slipping in range involved.
Overhaul transmission.
Broken hook-type sealrings. Replace sealrings.
Forward clutch piston seals leaking
or clutch plates slipping (all
upshifts).
Overhaul forward clutch and piston
assembly. Refer to Paragraph 6–8.
Sticking governor valve. Clean or replace governor screen
and/or governor. The governor may
be disassembled for cleaning and
inspection only if the kit consisting
of two governor weight pins and
cover gasket is available. Refer to
Paragraphs 5–3e, 5–3h(5), 6–5,
7–10a, and 7–11a.
C. Overheating in all Ranges
Overheating in all ranges Cooler lines restricted. Remove restrictions, clean or replace
lines. Refer to vehicle service man-
ual.
†
If unit is modified for split shaft PTO, all external circuitry must be removed before troubleshooting.
** Clutch slippage may be recognized by alternate racing and loading of the engine, which is at times, accompanied by a violent chatter.
Table 3–13. Troubleshooting Chart (cont’d)
Problem Probable Causes Suggested Remedies
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